This invention relates to an apparatus for making an elastic composite sheet.
Japanese Patent Application Disclosure No. 1998-245757 describes a process for making a sheet-like elastic composite comprising the steps of feeding a thermoplastic non-stretchable sheet into a nip between a heat-embossing roll formed on its peripheral surface with stripe-like ridges and grooves and a roll formed on it""s peripheral surface with the similar ridges and grooves adapted to be engaged with those of the heat-embossing roll to form the non-stretchable sheet with the corresponding ridges and grooves, and feeding a stretchable sheet together with the non-stretchable sheet formed with the ridges and grooves into a nip between the embossing roll and a flat roll to heat-seal the non-stretchable sheet only along the ridges formed thereon with the stretchable sheet.
The process described in the Japanese Patent Application Disclosure No. 1998-245757 requires two separate the steps, i.e., the step of forming the non-stretchable sheet with the ridges and grooves and the step of heat-sealing the non-stretchable sheet to the stretchable sheet. On the step of forming the non-stretchable sheet with the ridges and grooves, heat transfer inevitably occurs from the embossing roll and the roll having the ridges and the grooves adapted to be engaged with those of the embossing roll to substantially the whole surface of the non-stretchable sheet. Such heat transfer hardens the non-stretchable sheet and thereby deteriorates a touch expected for this non-stretchable sheet.
It is an object of this invention to provide an apparatus for making an elastic composite sheet enabling the elastic composite sheet to be made through a fewer number of steps than the prior art has required without a deterioration of a touch expected to be presented by the sheet.
According to one aspect of this invention, there is provided an apparatus for making an elastic composite sheet from a supply of stretchable and non-stretchable sheets, the apparatus comprising a pair of rolls opposed to each other adapted to bond respective surfaces of the non-stretchable sheets and a stretchable sheets placed one upon another and fed together into a nip of the pair of rolls to each other, wherein:
one of the rolls is formed on a peripheral surface thereof with a plurality of ridges projecting outward radially of the roll and extending circumferentially at predetermined intervals while the other of the rolls is formed on a peripheral surface thereof with a plurality of grooves recessed inward radially of the roll and extending also circumferentially at predetermined intervals; the ridges are engaged with the grooves with spaces left between surfaces of the ridges and the grooves to form the non-stretchable sheets on a surface of one of the rolls so as to conform thereto with a plurality of stripe-like crests extending in one direction and a plurality of flat troughs each defined between each pair of adjacent crests and the non-stretchable sheets are spaced apart from the plurality of grooves of the other of the rolls; and a bonder bonds the non-stretchable sheets only along the troughs thereof to the surface of the stretchable sheet.
The apparatus for making the elastic composite sheet"" as has been described hereinabove is advantageous in that the non-stretchable sheet can be formed on its surface with a plurality of stripe-like crests extending in one direction and a plurality of troughs each defined between each pair of adjacent crests extending also in the one direction and simultaneously the troughs of the non-stretchable sheet can be bonded to the surface of the stretchable sheet merely by feeding the non-stretchable sheet together with the stretchable sheet into the nip between a pair of rolls. In this way, the elastic composite sheet can be made through the minimum number of steps. The ridges and the grooves formed on the respective rolls are engaged with one another in a non-contact fashion such that the crests of the non-stretchable sheet is spaced apart from the plurality of troughs of the other of the rolls and therefore it is not apprehended that heat might be transferred to the crests of the non-stretchable sheet and deteriorate a touch presented by these crests of the nonstretchable sheet.